The present invention pertains generally to tracheal intubation, and more particularly to methods and apparatus for performing tracheal intubation on animals.
Tracheal intubation is commonly used in human patients during medical procedures in order to keep air passing into the lungs and to prevent foreign matter from entering the lungs. An endotracheal tube typically made from polyvinyl chloride, rubber, silicone, or the like is inserted into the trachea. A cuff on the tube is then inflated until the cuff seals off the trachea leaving only the endotracheal tube as the source of air to the lungs. As air is injected, an external pilot balloon also inflates thereby giving the doctor a subjective indication of the degree of cuff inflation.
Methods and devices for tracheal intubation are well known in the art. For example, U.S. Pat. No. 4,850,371 shows a non-invasive apparatus for continuously measuring the cardiac output and cardio-respiratory function including a gas sampling device which is inserted into the mouth of a human subject. The gas sampling device may be a disposable endotracheal tube or a smaller disposable mouthpiece. Each of these gas sampling devices is provided with a plurality of passages for sampling the lung gases and for continuously sampling the gas pressure on opposite sides of a capillary restriction member. A miniature motor pump mass spectrometer module is mounted on the upper end of the endotracheal tube or mouthpiece. Electronic circuitry connected to the mass spectrometer permits constant visual monitoring of the cardiac output and cardio-respiratory function.
U.S. Pat. No. 4,879,999 illustrates an endotracheal device provided with a calorimetric carbon dioxide indicator. The device functions to indicate the proper intratracheal placement of an endotracheal tube by detecting for the presence of carbon dioxide in expired air passing through the device.
U.S. Pat. No. 4,976,261 discloses an endotracheal tube for artificial ventilation which employs a primary cuff and a secondary cuff for locating and positioning the tube in the trachea of a patient. The secondary cuff employs a balloon sleeve which is located near the distal end of the tube. The secondary balloon sleeve is sealed against the tube in a reverse folded configuration. The tube wall includes a number of lumens which may be employed for various auxiliary functions.
U.S. Pat. No. 5,285,778 comprises an endotracheal tube having a main tube having a proximal end portion, distal end portion, and an inflatable annular cuff disposed on the main tube in sealed relation thereto adjacent to the distal end portion. An inflation tube extends from the distal end portion into the cuff. A viewing lens is located on the distal end portion and is optically coupled to a first optical fiber extending from the proximal end portion to the distal end portion. A viewing device is attached to a proximal end of the first optical fiber. An illumination port is located on the distal end portion coupled to a second optical fiber extending from the proximal end portion to the distal end portion. An illumination source is optically coupled to a proximal end of the second optical fiber. The extended insertion of the endotracheal tube and conditions of adjacent tissue can be viewed by means of the viewing device. A flushing tube extends from a flushing source adjacent the proximal end portion to a flushing outlet port located at the distal end portion adjacent the viewing lens for flushing mucous away from the viewing lens. In one embodiment, an auxiliary tube extends through a sealable port in a wall of the proximal end portion and slides through the sealable port, through the main tube, and out of the distal end portion. The auxiliary tube includes fiber optic illumination and viewing elements on a distal end portion and an inflatable annular cuff on the distal end portion.
U.S. Pat. No. 5,421,325 consists of an endotracheal assembly having an endotracheal tube, a malleable obturator inside the tube for enabling a placement of a distal end of the tube into a patient""s trachea, and a pressure-sensitive detector mounted to the obturator at the distal end. The purpose of the detector is to sense air or gas pressure above a predetermined threshold exerted against a distal end of the obturator upon placement of the tube with the obturator into the patient. Upon an initial insertion of the tube and the obturator into a patient""s trachea and possible manipulation of the tube and the obturator to effectuate a placement of the tube, a compressive pressure is exerted externally on the patient""s chest. The compressive pressure forces air out of the patient""s lungs and, if the tube and obturator assembly is properly placed, effectuates a change in the condition of the pressure sensor. That change in condition indicates that pressure above a predetermined level was exerted against the detector element.
U.S. Pat. No. 5,954,636 describes apparatus and method for selectively blocking respiratory airflow to a pediatric lung or a single lobe of the lung. The apparatus comprises an endotracheal tube providing a passage for a bronchoscope and a second flexible tube which is attached to the endotracheal tube. A bronchial blocker assembly, having a pair of axial passageways, is insertable into the second flexible tube. A stylet is inserted into one of the axial passageways to guide the endotracheal tube and bronchial blocker assembly along a pediatric patient""s windpipe. Means are provided for fixing the bronchial blocker assembly relative to the second axial passageway when the bronchial blocker assembly is in place.
Currently, endotracheal tubes used for dogs and cats are not veterinary specific. Instead, tubes designed for humans are used resulting in numerous problems. Small patients such as dogs and cats in particular are difficult to intubate since the opening of the larynx is obscured by the tongue base and is therefore difficult to see. Furthermore, laryngospasm, which is spastic closure of the larynx, occurs when the tube tip touches the larynx. It is usually necessary to apply topical anesthetic to minimize laryngospasm. Also, since the distal end of a typical endotracheal tube is relatively blunt, a narrow diameter stylet is placed in the lumen of the tube and passed into the opening of the larynx to force it slightly open. The endotracheal tube is then slid along the stylet to achieve intubation. Use of a stylet can potentially traumatize the trachea. Additionally, a larnygoscope is usually needed to force the epiglottis down, see the laryngeal opening, and verify that the tube has been placed in the larynx rather than the esophagus. Erroneous placement of the endotracheal tube in the esophagus is a major cause of anesthetic death and disability. Also, the inflation pressure within the cuff is critical. Insufficient inflation can allow saliva, vomit, or other foreign matter to seep into the lungs, with potentially fatal consequences. Conversely, excessive pressure in the cuff can rupture the trachea, or damage the tracheal lining, particularity in the case of cats. Current pilot balloons offer only subjective means of judging cuff inflation pressure
In view of problems discussed above, a need exists for an endotracheal tube specificially designed for use on small animals which eliminates the problems associated with using tubes designed for humans.
The present invention is directed to methods of tracheal intubation and associated endotracheal tubes specifically designed for animals. The endotracheal tube is angled in zigzag fashion so as to force the epiglottis down during intubation and provide better visibility of the trachea. The endotracheal tube also includes a tapered pointed end which serves as an integrated stylet. The tapered end allows the tube to pass more easily between the arytenoid cartilages of the larynx during laryngospasm. This eliminates the need for a separate stylet. The endotracheal tube further includes a quantitative pressure sensor for determining the pressure within the inflatable cuff, thereby preventing both over inflation and under inflation.
In accordance with a preferred embodiment of the invention, a method for performing tracheal intubation on an animal, includes:
(a) providing an animal having a mouth and an epiglottis;
(b) providing an endotracheal tube having:
an elongated firm body having a proximal portion and a distal portion;
a double bend disposed in the body between the proximal and distal portions, so that the distal portion is transversely displaced with respect to the proximal portion; and,
the distal portion having an outward facing surface for depressing the epiglottis of the animal;
(c) inserting the distal end of the endotracheal tube into the mouth of the animal; and,
(d) using the outward facing surface to depress the epiglottis of the animal.
Another preferred method for performing tracheal intubation on an animal includes:
(a) providing an animal having a larynx having arytenoid cartilages and a trachea;
(b) providing an endotracheal tube having:
an elongated body having a proximal portion and a distal portion;
the distal portion having a tapered end for passing the endotracheal tube through the arytenoid cartilages and into the trachea; and,
the tapered end forming an angle which is less than 25xc2x0; and,
(c) using the tapered end to pass the endotracheal tube through the arytenoid cartilages and into the trachea of the animal.
Another preferred method for performing tracheal intubation on an animal includes:
(a) providing an animal having a trachea;
(b) providing an endotracheal tube including:
an inflatable cuff;
a pilot balloon connected to the cuff; and,
a pilot balloon including a pressure indicator for measuring air pressure within the cuff;
(c) inserting the cuff into the trachea of animal;
(d) inflating the inflatable cuff; and,
(h) using the pressure indicator to measure air pressure within the cuff.
Other aspects of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.